Thoroughly fed up but refusing to give in, the residents of the Coal River valley in West Virginia endure earsplitting explosions, raining boulders, toxic sludge and poisoned wells. Their tormentor is the union-busting, environmental-law-flouting Massey Energy Company and its use of the controversial mining strategy called mountaintop removal. Their solution is a grass-roots campaign to force the company to cease and desist, and Bill Haney’s furious documentary, “The Last Mountain,” is completely on board.

But the fate of the peak in question — which Massey plans to decapitate like a perfectly boiled egg — is only part of this film’s heartbreaking agenda. The rest is an environmental horror story filled with imperiled schoolchildren, silica dust, and cancer and autism clusters that defy statistical logic. Coming down like a ton of dross on those he believes responsible, Mr. Haney weaves scientific testimony, contentious debates and moving personal stories into a persuasive indictment of Massey in particular and fossil-derived energy in general.

While on-screen notes inform us that hundreds of Appalachian mountains and a million acres of forest have already been flattened, the film draws power from the pain and debris left behind. Doleful guitar twangs accompany shocking aerial views of pancaked wastelands bristling with jagged rocks and scrubby grasses. And if Mr. Haney sometimes struggles to find focus, he has no trouble locating heroes, including the doggedly energetic Robert F. Kennedy Jr. and a slew of stalwart locals and fearless outsiders. The black heart of coal country — and, as the film shows, our national energy debate — has never seemed so in need of white knights.